/* Copyright (c) 2006-2011 by OpenLayers Contributors (see authors.txt for 
 * full list of contributors). Published under the Clear BSD license.  
 * See http://svn.openlayers.org/trunk/openlayers/license.txt for the
 * full text of the license. */

/*
 * Development supported by a R&D grant DC08P02OUK006 - Old Maps Online
 * (www.oldmapsonline.org) from Ministry of Culture of the Czech Republic.
 */


/**
 * @requires OpenLayers/Layer/Grid.js
 */

/**
 * Class: OpenLayers.Layer.Zoomify
 *
 * Inherits from:
 *  - <OpenLayers.Layer.Grid>
 */
OpenLayers.Layer.Zoomify = OpenLayers.Class(OpenLayers.Layer.Grid, {

    /**
     * Property: url
     * {String} URL for root directory with TileGroupX subdirectories.
     */
    url: null,

    /**
     * Property: size
     * {<OpenLayers.Size>} The Zoomify image size in pixels.
     */
    size: null,

    /**
     * APIProperty: isBaseLayer
     * {Boolean}
     */
    isBaseLayer: true,

    /**
     * Property: standardTileSize
     * {Integer} The size of a standard (non-border) square tile in pixels.
     */
    standardTileSize: 256,

    /** 
     * Property: tileOriginCorner
     * {String} This layer uses top-left as tile origin
     **/
    tileOriginCorner: "tl",

    /**
     * Property: numberOfTiers
     * {Integer} Depth of the Zoomify pyramid, number of tiers (zoom levels)
     *                          - filled during Zoomify pyramid initialization.
     */
    numberOfTiers: 0,

    /**
     * Property: tileCountUpToTier
     * {Array(Integer)} Number of tiles up to the given tier of pyramid.
     *                          - filled during Zoomify pyramid initialization.
     */
    tileCountUpToTier: new Array(),

    /**
     * Property: tierSizeInTiles
     * {Array(<OpenLayers.Size>)} Size (in tiles) for each tier of pyramid.
     *                          - filled during Zoomify pyramid initialization.
     */
    tierSizeInTiles: new Array(),

    /**
     * Property: tierImageSize
     * {Array(<OpenLayers.Size>)} Image size in pixels for each pyramid tier.
     *                          - filled during Zoomify pyramid initialization.
     */
    tierImageSize: new Array(),

    /**
     * Constructor: OpenLayers.Layer.Zoomify
     *
     * Parameters:
     * name - {String} A name for the layer.
     * url - {String} - Relative or absolute path to the image or more
     *        precisly to the TileGroup[X] directories root.
     *        Flash plugin use the variable name "zoomifyImagePath" for this.
     * size - {<OpenLayers.Size>} The size (in pixels) of the image.
     * options - {Object} Hashtable of extra options to tag onto the layer
     */
    initialize: function(name, url, size, options) {

        // initilize the Zoomify pyramid for given size
        this.initializeZoomify( size );

        var newArguments = [];
        newArguments.push(name, url, size, {}, options);

        OpenLayers.Layer.Grid.prototype.initialize.apply(this, newArguments);
    },

    /**
     * Method: initializeZoomify
     * It generates constants for all tiers of the Zoomify pyramid
     *
     * Parameters:
     * size - {<OpenLayers.Size>} The size of the image in pixels
     *
     */
    initializeZoomify: function( size ) {

        var imageSize = size.clone();
        var tiles = new OpenLayers.Size(
            Math.ceil( imageSize.w / this.standardTileSize ),
            Math.ceil( imageSize.h / this.standardTileSize )
            );

        this.tierSizeInTiles.push( tiles );
        this.tierImageSize.push( imageSize );

        while (imageSize.w > this.standardTileSize ||
               imageSize.h > this.standardTileSize ) {

            imageSize = new OpenLayers.Size(
                Math.floor( imageSize.w / 2 ),
                Math.floor( imageSize.h / 2 )
                );
            tiles = new OpenLayers.Size(
                Math.ceil( imageSize.w / this.standardTileSize ),
                Math.ceil( imageSize.h / this.standardTileSize )
                );
            this.tierSizeInTiles.push( tiles );
            this.tierImageSize.push( imageSize );
        }

        this.tierSizeInTiles.reverse();
        this.tierImageSize.reverse();

        this.numberOfTiers = this.tierSizeInTiles.length;

        this.tileCountUpToTier[0] = 0;
        for (var i = 1; i < this.numberOfTiers; i++) {
            this.tileCountUpToTier.push(
                this.tierSizeInTiles[i-1].w * this.tierSizeInTiles[i-1].h +
                this.tileCountUpToTier[i-1]
                );
        }
    },

    /**
     * APIMethod:destroy
     */
    destroy: function() {
        // for now, nothing special to do here.
        OpenLayers.Layer.Grid.prototype.destroy.apply(this, arguments);

        // Remove from memory the Zoomify pyramid - is that enough?
        this.tileCountUpToTier.length = 0;
        this.tierSizeInTiles.length = 0;
        this.tierImageSize.length = 0;

    },

    /**
     * APIMethod: clone
     *
     * Parameters:
     * obj - {Object}
     *
     * Returns:
     * {<OpenLayers.Layer.Zoomify>} An exact clone of this <OpenLayers.Layer.Zoomify>
     */
    clone: function (obj) {

        if (obj == null) {
            obj = new OpenLayers.Layer.Zoomify(this.name,
                                           this.url,
                                           this.size,
                                           this.options);
        }

        //get all additions from superclasses
        obj = OpenLayers.Layer.Grid.prototype.clone.apply(this, [obj]);

        // copy/set any non-init, non-simple values here

        return obj;
    },

    /**
     * Method: getURL
     *
     * Parameters:
     * bounds - {<OpenLayers.Bounds>}
     *
     * Returns:
     * {String} A string with the layer's url and parameters and also the
     *          passed-in bounds and appropriate tile size specified as
     *          parameters
     */
    getURL: function (bounds) {
        bounds = this.adjustBounds(bounds);
        var res = this.map.getResolution();
        var x = Math.round((bounds.left - this.tileOrigin.lon) / (res * this.tileSize.w));
        var y = Math.round((this.tileOrigin.lat - bounds.top) / (res * this.tileSize.h));
        var z = this.map.getZoom();

        var tileIndex = x + y * this.tierSizeInTiles[z].w + this.tileCountUpToTier[z];
        var path = "TileGroup" + Math.floor( (tileIndex) / 256 ) +
            "/" + z + "-" + x + "-" + y + ".jpg";
        var url = this.url;
        if (OpenLayers.Util.isArray(url)) {
            url = this.selectUrl(path, url);
        }
        return url + path;
    },

    /**
     * Method: getImageSize
     * getImageSize returns size for a particular tile. If bounds are given as
     * first argument, size is calculated (bottom-right tiles are non square).
     *
     */
    getImageSize: function() {
        if (arguments.length > 0) {
            var bounds = this.adjustBounds(arguments[0]);
            var res = this.map.getResolution();
            var x = Math.round((bounds.left - this.tileOrigin.lon) / (res * this.tileSize.w));
            var y = Math.round((this.tileOrigin.lat - bounds.top) / (res * this.tileSize.h));
            var z = this.map.getZoom();
            var w = this.standardTileSize;
            var h = this.standardTileSize;
            if (x == this.tierSizeInTiles[z].w -1 ) {
                var w = this.tierImageSize[z].w % this.standardTileSize;
            };
            if (y == this.tierSizeInTiles[z].h -1 ) {
                var h = this.tierImageSize[z].h % this.standardTileSize;
            };
            return (new OpenLayers.Size(w, h));
        } else {
            return this.tileSize;
        }
    },

    /**
     * APIMethod: setMap
     * When the layer is added to a map, then we can fetch our origin
     *    (if we don't have one.)
     *
     * Parameters:
     * map - {<OpenLayers.Map>}
     */
    setMap: function(map) {
        OpenLayers.Layer.Grid.prototype.setMap.apply(this, arguments);
        this.tileOrigin = new OpenLayers.LonLat(this.map.maxExtent.left,
                                                this.map.maxExtent.top);
    },

    /**
     * Method: calculateGridLayout
     * Generate parameters for the grid layout. This
     *
     * Parameters:
     * bounds - {<OpenLayers.Bound>}
     * origin - {<OpenLayers.LonLat>}
     * resolution - {Number}
     *
     * Returns:
     * Object containing properties tilelon, tilelat, tileoffsetlat,
     * tileoffsetlat, tileoffsetx, tileoffsety
     */
    calculateGridLayout: function(bounds, origin, resolution) {
        var tilelon = resolution * this.tileSize.w;
        var tilelat = resolution * this.tileSize.h;

        var offsetlon = bounds.left - origin.lon;
        var tilecol = Math.floor(offsetlon/tilelon) - this.buffer;
        var tilecolremain = offsetlon/tilelon - tilecol;
        var tileoffsetx = -tilecolremain * this.tileSize.w;
        var tileoffsetlon = origin.lon + tilecol * tilelon;

        var offsetlat = origin.lat - bounds.top + tilelat;
        var tilerow = Math.floor(offsetlat/tilelat) - this.buffer;
        var tilerowremain = tilerow - offsetlat/tilelat;
        var tileoffsety = tilerowremain * this.tileSize.h;
        var tileoffsetlat = origin.lat - tilelat*tilerow;

        return {
          tilelon: tilelon, tilelat: tilelat,
          tileoffsetlon: tileoffsetlon, tileoffsetlat: tileoffsetlat,
          tileoffsetx: tileoffsetx, tileoffsety: tileoffsety
        };
    },

    CLASS_NAME: "OpenLayers.Layer.Zoomify"
});
